BeMicro MAX10 does not keep program after power down?

MAX10 won't store it's configuration image if you're only programming it with the .sof file. You need to program it's FLASH memory, from which it boots at power up. You can do this as follows:

1) In Quartus, select 'File' -> 'Convert Programming Files...'.

2) Change the 'Programming file type' to 'Programmer Object File (.opf)'

3) Ignore the 'Configuration device' but set the 'Mode:' to 'Internal Configuration'.

4) In the 'Input files to convert' window, select 'SOF Data' and 'Add File...'. Select your '.sof' image.

5) Click 'Generate'.

In the programmer, load up your new '.pof' and check the 'Program/Configure' box next to 'CFM0'. Then Start. This will put your image into FLASH (rather slowly) from which your MAX10 will boot when you power the board up.

I've not had cause to boot a Nios from a MAX10 device yet. However, an730 - nios ii processor booting methods in max 10 fpga devices (https://www.altera.com/en_us/pdfs/literature/an/an730.pdf) discusses it at length. I'm sure it'll help.

Regards,

Alex